Wind Law Proposal for Aircraft Control in Turbulence

ifasd2024 Tracking Number 8

In the frame of the “Aircraft Control in Turbulence” this article is highlighting an innovative methodology for the passenger’s comfort improvement and aircraft dynamic loads reduction. Actually, this methodology has been developed by using the linear “Quasi-static” short period model and lies in the coupling of the lift and pitching moment equations. This coupling has been made possible by the analytical “Aerodynamic Crossed-Products” identification based on the Doublet Lattice method in the low frequency domain, even though never mentioned in flight mechanics handbooks. Then, based on this preliminary analytical identification, this coupling led to a unique equation, seen as energetical type and named “Fundamental Equation of Aircraft’s Dynamic” or “Equation of Conservation”. This fundamental equation, at the heart of the Aircraft’s Dynamic, is a function of the flight mechanics parameters such as, the angle of attack derivative, the pitch rate and the pitch rate derivative, but also a function of several fundamental aerodynamic “Neutral points” which are governing the global Dynamic Aircraft response. In a first step, this equation has been highlighted with only the elevators and ailerons control surfaces for basic control laws tuning and then in a second step, the wind effect has been introduced leading to the fundamental equation with both control surfaces and wind effect as model inputs. Finally, it has been possible to define a global control surfaces order that enables to minimize the wind effect in the aircraft dynamic response. In a first part, this article presents the “keys steps” of the theoretical development leading to the “Fundamental Equation of Aircraft’s Dynamic in Turbulence”. In a second part, this concept is illustrated by the linear short period model time responses, with a focus on load factor time histories. This preliminary study constitutes a first step towards a more realistic approach and more complex simulations by considering on one hand an aeroelastic model with rigid and flexible modes and on the other hand by defining this specific control law in turbulence accounting for actuators characteristics, time delays.